Dr. Brewster's suicide takes a particular twist when the pathologist determines that he had also been bound and gagged. The Brewsters both medical doctors ran a private clinic and their son John who lived at home is doctoral candidate in philosophy. One possible suspect is Michael Steppings who threatened the Brewsters and their nurse after his daughter suffered severe side-effects and is now in a vegetative state from a botched operation two years previously. The forensics lab determines that one of Steppings's threatening letters was altered and Morse learns that Brewster may at one time been having an affair so he must consider another possible motive for murder.